Present addresses: Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Hydrological process controls on nitrogen export during storm events in an agricultural watershed
Version of Record online: 1 MAR 2010
© 2010 Japanese Society of Soil Science and Plant Nutrition
Soil Science & Plant Nutrition
Volume 56, Issue 1, pages 72–85, February 2010
How to Cite
JIANG, R., WOLI, K. P., KURAMOCHI, K., HAYAKAWA, A., SHIMIZU, M. and HATANO, R. (2010), Hydrological process controls on nitrogen export during storm events in an agricultural watershed. Soil Science & Plant Nutrition, 56: 72–85. doi: 10.1111/j.1747-0765.2010.00456.x
Department of Biological Environment, Akita Prefectural University, Akita 010-0195, Japan.
- Issue online: 1 MAR 2010
- Version of Record online: 1 MAR 2010
- Received 30 July 2009. Accepted for publication 5 January 2010.
- first flush;
- flow paths;
- storm events
The dynamic characteristics of nitrogen (N) and suspended solids (SS) were investigated in stream water during four storm events in 2003 in the Shibetsu watershed, eastern Hokkaido, Japan. Analysis showed that total nitrogen (TN), nitrate-N (-N), dissolved organic nitrogen (DON), particulate nitrogen (PN) and SS concentrations all peaked sharply during the rising limb of the discharge hydrograph, but peaks in PN and SS were more significant than the peak in dissolved N. Particulate N and SS consistently displayed clockwise hysteresis with higher concentrations during rising flows, whereas -N and DON showed different patterns among the storms depending on the antecedent soil moisture. An M (V) curve, defined as the nutrient mass distribution versus the volume of discharge, showed that a “first flush” of PN, -N, DON and SS was observed; however, the distribution of nutrient loads in the discharge was different. Particulate N and SS had a shorter flushing characteristic time constant (t1/e, defined as the time interval required for a decline in nutrient concentrations in discharge water to e−1 [37%] of their initial concentrations), but contributed 80% of fluxes during the first 50% of the discharge, whereas the longer flush time (t1/e) of -N and DON with slowly decreased concentrations led to half loads during the recession of the discharge. These data indicate that flush mechanisms might be distinguished between particulate nutrients and dissolved N. Analysis showed that the concentrations of PN and SS derived from soil erosion were related to surface run-off. In contrast, -N originated from the near-surface soil layer associated with the rising shallow groundwater table and mainly flushed with subsurface run-off. The different flushing mechanisms implied that different watershed best management practices should be undertaken for effectively mitigating water quality degradation.